FAQ: Can you hear the Shuttle’s Sonic Boom inside the Shuttle?

ANSWER: No, you cannot. The crew cannot hear the sonic booms (there are two of them) when the Orbiter passes through Mach 1 and becomes subsonic over Cape Canaveral.

The booms are the interpretation of the human ear on the ground when hit by the expanding shock waves at the nose and at the tail of the Shuttle Orbiter. These shocks happen when pressure of the air stream around the Shuttle changes too abruptly to be able to dissipate (i.e. spread out) in accordance with the (slower) natural ability of the air to handle it – its local “speed of sound”.

These shocks would appear as a cone each, with the object generating it at its point, and spreading out behind it while being dragged along by it. There’s a shock generated by the nose and another by the tailing edge of the tail fin. When the bottom portions of these conically spreading wakes hit the ground, the ear drum perceives the sudden pressure change as a boom (it’s more like a crack, really – thus: CRACK — CRACK always announces the Shuttle a few minutes before it lands). If you measure the pressure jumps, their signature look like the letter “N”, and that’s why aerodynamicists call the phenomenon the “N wave”.

Since the crew is inside the cabin and not subjected to the expanding shock wave, it cannot hear the booms.